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websockify 0.6.0

websockify was formerly named wsproxy and was part of the[noVNC](https://github.com/kanaka/noVNC) project.

At the most basic level, websockify just translates WebSockets trafficto normal socket traffic. Websockify accepts the WebSockets handshake,parses it, and then begins forwarding traffic between the client andthe target in both directions.

If you are a websockify developer/integrator/user (or want to be)please join the <a<br>href="https://groups.google.com/forum/?fromgroups#!forum/novnc">noVNC/websockifydiscussion group</a>

Bugs and feature requests can be submitted via [githubissues](https://github.com/kanaka/websockify/issues)

If you want to show appreciation for websockify you could donate to a greatnon-profits such as: [CompassionInternational](http://www.compassion.com/) [SIL](http://www.sil.org),[Habitat for Humanity](http://www.habitat.org), [Electronic FrontierFoundation](https://www.eff.org/) [Against MalariaFoundation](http://www.againstmalaria.com/) [Nothing ButNets](http://www.nothingbutnets.net/) etc. Please tweet <a<br>href="http://www.twitter.com/noVNC">@noVNC if you do.

### WebSockets binary data

Starting with websockify 0.5.0, only the HyBi / IETF6455 WebSocket protocol is supported.

Websockify negotiates whether to base64 encode traffic to and from theclient via the subprotocol header (Sec-WebSocket-Protocol). The validsubprotocol values are 'binary' and 'base64' and if the client sendsboth then the server (the python implementation) will prefer 'binary'.The 'binary' subprotocol indicates that the data will be sent rawusing binary WebSocket frames. Some HyBi clients (such as the Flashfallback and older Chrome and iOS versions) do not support binary datawhich is why the negotiation is necessary.

### Encrypted WebSocket connections (wss://)

To encrypt the traffic using the WebSocket 'wss://' URI scheme youneed to generate a certificate for websockify to load. By default websockifyloads a certificate file name `self.pem` but the `--cert=CERT` option canoverride the file name. You can generate a self-signed certificate usingopenssl. When asked for the common name, use the hostname of the server wherethe proxy will be running:

The `include/websock.js` Javascript library library provides a Websockobject that is similar to the standard WebSocket object but Websockenables communication with raw TCP sockets (i.e. the binary stream)via websockify. This is accomplished by base64 encoding the datastream between Websock and websockify.

Websock has built-in receive queue buffering; the message eventdoes not contain actual data but is simply a notification thatthere is new data available. Several rQ* methods are available toread binary data off of the receive queue.

The Websock API is documented on the [websock.js API wiki page](https://github.com/kanaka/websockify/wiki/websock.js)

See the "Wrap a Program" section below for an example of using Websockand websockify as a browser telnet client (`wstelnet.html`).

### Additional websockify features

These are not necessary for the basic operation.

* Daemonizing: When the `-D` option is specified, websockify runs in the background as a daemon process.

* SSL (the wss:// WebSockets URI): This is detected automatically by websockify by sniffing the first byte sent from the client and then wrapping the socket if the data starts with '\x16' or '\x80' (indicating SSL).

* Session recording: This feature that allows recording of the traffic sent and received from the client to a file using the `--record` option.

* Mini-webserver: websockify can detect and respond to normal web requests on the same port as the WebSockets proxy and Flash security policy. This functionality is activate with the `--web DIR` option where DIR is the root of the web directory to serve.

* Wrap a program: see the "Wrap a Program" section below.

### Implementations of websockify

The primary implementation of websockify is in python. There areseveral alternate implementations in other languages (C, Node.js,Clojure, Ruby) in the `other/` subdirectory (with varying levels offunctionality).

In addition there are several other external projects that implementthe websockify "protocol". See the alternate implementation [FeatureMatrix](https://github.com/kanaka/websockify/wiki/Feature_Matrix) formore information.

### Wrap a Program

In addition to proxying from a source address to a target address(which may be on a different system), websockify has the ability tolaunch a program on the local system and proxy WebSockets traffic toa normal TCP port owned/bound by the program.

The is accomplished with a small LD_PRELOAD library (`rebind.so`)which intercepts bind() system calls by the program. The specifiedport is moved to a new localhost/loopback free high port. websockifythen proxies WebSockets traffic directed to the original port to thenew (moved) port of the program.

The program wrap mode is invoked by replacing the target with `--`followed by the program command line to wrap.

`./run 2023 -- PROGRAM ARGS`

The `--wrap-mode` option can be used to indicate what action to takewhen the wrapped program exits or daemonizes.

Here is an example of using websockify to wrap the vncserver command(which backgrounds itself) for use with[noVNC](https://github.com/kanaka/noVNC):

`./run 5901 --wrap-mode=ignore -- vncserver -geometry 1024x768 :1`

Here is an example of wrapping telnetd (from krb5-telnetd). telnetdexits after the connection closes so the wrap mode is set to respawnthe command:

`sudo ./run 2023 --wrap-mode=respawn -- telnetd -debug 2023`

The `wstelnet.html` page demonstrates a simple WebSockets based telnetclient (use 'localhost' and '2023' for the host and portrespectively).

### Building the Python ssl module (for python 2.5 and older)

* Install the build dependencies. On Ubuntu use this command:

`sudo aptitude install python-dev bluetooth-dev`

* At the top level of the websockify repostory, download, build and symlink the ssl module: